This invention relates to sound reproduction systems; and more particularly relates to a novel an improved system of the type described for enhancing stereophonic perception of sound upon the ear of the listener.
Numerous systems have been devised for improving the quality of sound reproduced from an audio source. Typical of such systems are the stereophonic and quadraphnic systems in which two or more speakers are spaced at intervals about a room and the sound produced is radiated from different angles or locations toward the listener. In the past, considerable attention has been given to the quality of recording the sound as well as the quality of equipment employed to refine the sound when reproduced for the listening pleasure of an audience.
One typical approach is that disclosed in U.S. Pat. No. 4,612,663 to K. A. Holbrook et al in which four speakers are arranged in a generally T-shaped configuration with left, front and right speakers in a vertical plane and a rear speaker behind that plane. The system is designed to generate both in-phase and out-of-phase signals (L-R or R-L) to the front and back speakers in order to achieve higher quality or realism in the sound. Another U.S. Pat. No. 3,757,047 to R. Ito et al, utilizes signals which are generated out-of-phase with respect to one another in a loudspeaker arrangement. U.S. Pat. No. 3,697,692 to D. Hafler similarly employs out-of-phase signals with various different loudspeaker arrangements to enhance the realism of sound. U.S. Pat. No. 3,745,254 to K. Ohta et al has an arrangement of four loudspeakers operated from a two-channel source in which the four speakers are equidistantly spaced apart and receive different signals with a phase shift introduced between the signals but requires special equipment to generate the out-of-phase signals.
In accordance with the present invention, it has been found that not only may the manner of generating a phase relationship between signals be greatly improved but also the spacing, and location between pairs of standard stereophonic speakers and auxiliary speakers to greatly enhance the dimensional reconstruction of the sound and its effect on the listening audience.